Ever Deepening

Cosmology

As mentioned above, the universe is the experiment of last resort for
particle physicists who can no longer command the political will to build
larger particle accelerators (the last U.S. project was mothballed when
projections ran to $20 billion). Cosmology is a rapidly evolving field,
and astrophysicists are constantly fielding instruments that improve the
breadth and detail of our observations of the universe.

From this, it would seem that any inferences for particle theory might
be subject to frequent revision. In fact, the history of dark matter
exhibits just this kind of instability. Every year, there seem to be new
and progressively more contradictory constraints on its properties.

Therefore, the list below can only be considered a sketch of this
complex and rapidly developing field. It consists of those results crude
enough to have survived the observational revolutions of the last 25
years. The epithet (crude) should be taken as a characterization
of my currency in this area: much more sensitive measurements are being
obtained by improved satellite- and ground-based observatories. I am not
an expert in these areas.

We observe no galactic-scale defects in the vacuum distribution of
the gauge fields. Theoretically, the 10 spatial dimensions of
super-string theory are necessary to suppress topological defects in the
gauge fields that would give rise to galactic-scale structures.

The universe evolved as a cool bubble in a soup of particles and
fields originally heated beyond the Planck Scale. Beyond this energy,
particles readily can pierce the resistance to motion along the seven
spatial dimensions that have collapsed in our era.

The universe is gravitationally closed. Specifically, the expansion
of the universe, at very early times, is determined by the release of
energy from fields that are converted to mass precisely sufficient to
stop the expansion.

The most directly evident consequence of the expansionary epochs of
the Big Bang is the Hubble expansion. Light originating from distant
cosmological objects is "red-shifted" in a manner consistent with the
predictions of relativity theory for rapidly moving objects. That we
appear to be in the center of the expanding field is readily understood
from the predicted homogeneity of the expansion.

Black-body residue (microwave background radiation) is consistent
with a phase transition that occurred when the charged particles
(electrons and protons) combined to form atoms, and the expected growth
in the size of the universe since that epoch.